We have investigated the oxidation of the carcinogenic nitrosamine, N- nitroso-dimethylamine (NDMA), by Fenton-derived intermediates and by hydroxyl radical. Spin trap studies for the reaction between NDMA and hydroxyl radical indicated that novel intermediates were involved in the degradation of this nitrosamine. This has led us to important mechanistic conclusions regarding the Fenton reaction, including the determination of a unique oxidative pathway not involving hydroxyl radical. A new analytic methodology was developed which allows the quantification, in a single chromatographic run, of NDMA and its putative amine-containing metabolites. This methodology should facilitate the testing of animal treatment regimens designed to enhance the denitrosation (presumably detoxicating) pathway of NDMA metabolism at the expense of the demethylation (activating) pathway.